Rebtel, which says it is the world's second-biggest provider of voice calls over the Internet after Skype, could go for a stock market listing in the next two to three years if it meets its growth targets, its CEO said.

Voice over Internet (VoIP) players like Rebtel (Stockholm, Sweden) and Skype (Luxembourg) offer calls for free or at a fraction of the cost charged by traditional telecom operators and have been growing rapidly in recent years.

While Skype, bought by Microsoft Corp (Seattle, USA) for $8.5 billion in 2011, initially focused on video calls over PCs, Rebtel's service is accessed by a mobile phone app.

It has around 20 million users compared with Skype's 145 million.

Chief Executive Andreas Bernstrom sees revenue rising to more than $100 million this year from $80 million in 2012, and to between $150 million and $200 million in three years, he told Reuters.

By that time its user base should have grown to 50 million, he said.

"Listing is certainly an option," Bernstrom said. "My view is that in a couple of years, if the market allows it, that might be an interesting option."

Rebtel has been profitable since 2010.

VoIP players are creating a major headache for traditional telecom companies, whose voice calls make up the bulk of revenue. Plunging prices have offset growth from video downloads and mobile internet use on smartphones and tablets.

Some operators, like Sweden's TeliaSonera (Stockholm, Sweden), initially tried to block their subscribers from using VoIP and then mulled charging extra, but now they are having to adapt pricing and business models to the new competitive landscape.

Bernstrom said the company, majority owned by its founders Hjalmar Winbladh and Jonas Lindroth and backed by UK venture capital funds Index Ventures and Balderton Capital, has three major strategies to boost growth.

The first is the launch of a calling feature for apps which will allow online poker players to chat for free during games and internet daters to share more than emails and pictures.

The second strand is money transfer, where Rebtel intends to take on the likes of Western Union (Englewood, USA) and Moneygram (Dallas, USA) in what Bernstrom said was a $480 billion-a-year market.

Finally, the company intends to expand and develop its products into stand-alone apps, such as one that would allow travelers to avoid roaming charges.

"If the business is earning $150 to 200 million with a 15 percent EBITDA margin, then the business is worth a lot of money," Bernstrom said.